Various measures have been invented and taken to prevent illicit activities including the sale of counterfeit articles and the illicit use of forged or counterfeit certificates and notes. The attachment of seals to articles has been a conventional method of authenticating genuine articles. Seals with a relief hologram formed by recording interference fringes in fine irregularities are used as means for authentication because relief holograms can be easily mass-produced.
A label proposed in, for example, Patent Document 1 is formed by sequentially forming a diffraction grating pattern layer, an embossed diffraction grating pattern (relief hologram), an evaporated metal layer and an adhesive layer in that order on a lower surface of a transparent plastic base.
Patent Document 1: JP 11-305666 (p. 3, FIG. 1)
The label including a relief hologram mentioned in Patent Document 1 is resistant to forgery and counterfeiting, though not quite satisfactorily. However, since the relief hologram forming method is generally known, authenticating means more secure against forgery and counterfeiting have been desired. Since the evaporated metal layer is formed over the entire lower surface in the label mentioned in Patent Document 1, the label assumes a metallic color, which makes it difficult to easily see an information recording part.
Use of a volume hologram highly resistant to forgery and counterfeiting instead of a relief hologram may be effective. However, when a label provided with a volume hologram is attached to an article, and characters are printed on the label, it is possible that the characters cannot be printed in a satisfactory print quality because a step is formed at the boundary of a region in which the volume hologram is formed and a region around the hologram region. If a volume hologram is formed on a base by decalcomania using a transfer sheet, the adverse effect of the step is reduced. However, the volume hologram must have a capability of being clearly cut out in a desired shape (hereinafter referred to as “severability”) when the volume hologram is transferred from the transfer sheet to the base (hereinafter, referred to as “spot-transfer”).
Since the volume hologram is a means for verifying genuineness, it is necessary to confirm the spot-transfer of the volume hologram by some method.